The present invention relates to a method for the desorption of a material which adsorbs moisture, and to a device for implementing the method.
DE-A 41 33 917 discloses a device for air conditioning a passenger cabin of a motor vehicle, which device comprises two reactors with a sorbent disposed therein. The reactors serve for drying a circulating air stream, with only one of the reactors connected in parallel being operational at any one time. The other reactor is subject to desorption at the same time, to which end it is supplied with a heated air stream which flows through the sorbent and drives off the moisture adsorbed therein. For the purpose of heating the air stream, a heat exchanger is provided wherein exhaust gas heat, refrigerant heat or the like can be supplied to the air stream.
The desorption in a reactor is effected in such a way that the air stream heated to a sufficiently high temperature flows through the reactor that is subject to desorption during a fixed period. The period is selected based on empirical values and is a function of the air flow rate of the heated air stream and of the heating energy available. Since heating energy is available only to a limited extent, it is necessary, in order to achieve an adequate inlet temperature of the heated air stream, for the air flow rate thereof to be adjusted accordingly.
The desorption time for a reactor significantly determines the design of the reactors connected in parallel, which are operated alternately. It is necessary to ensure that, over the entire desorption time for the one reactor, the other reactor guarantees the drying required of the air stream supplied, even under unfavorable conditions. To this end, a certain amount of sorbent is required.